Mechanism for dividing tissue in a hemostat-style instrument

ABSTRACT

Open electrosurgical forceps for sealing tissue are provided which include first and second shaft portions pivotably associated with one another. Each shaft portion has a jaw member disposed at a distal end thereof. Each of the jaw members includes an electrically conductive sealing surface adapted to communicate electrosurgical energy through tissue held therebetween and a slot formed through the sealing surface thereof. The forceps includes a cutting mechanism operatively associated with the first and second jaw members. The cutting mechanism includes a cutting element disposed within the slot of the at least one jaw member, the cutting element being movable from a first position wherein the cutting element is retracted within the at least one jaw member and a second position in which the cutting element at least partially projects from a sealing surface of the at least one jaw member.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority to U.S. ProvisionalApplication Ser. No. 60/616,968 filed on Oct. 8, 2004 entitled“MECHANISM FOR DIVIDING TISSUE IN A HEMOSTAT-STYLE INSTRUMENT” theentire contents of which being incorporated by reference herein.

BACKGROUND

The present disclosure relates to forceps used for open surgicalprocedures. More particularly, the present disclosure relates to an openforceps which applies a combination of mechanical clamping pressure andelectrosurgical energy to seal tissue and a cutting device which isselectively activatable to sever tissue.

TECHNICAL FIELD

A forceps is a plier-like instrument which relies on mechanical actionbetween its jaws to grasp, clamp and constrict vessels or tissuetherebetween. So-called “open forceps” are commonly used in opensurgical procedures whereas “endoscopic forceps” or “laparoscopicforceps” are, as the name implies, used for less invasive endoscopicsurgical procedures. Electrosurgical forceps (open or endoscopic)utilize both mechanical clamping action and electrical energy to effecthemostasis by heating tissue and blood vessels to coagulate and/orcauterize tissue.

Certain surgical procedures require more than simply cauterizing tissueand rely on the unique combination of clamping pressure, preciselycontrolling the application of electrosurgical energy and the gapdistance (i.e., distance between opposing jaw members or opposingconducting surfaces when closed about tissue) to “seal” tissue, vesselsand certain vascular bundles.

Vessel sealing or tissue sealing is a recently-developed technologywhich utilizes a unique combination of radiofrequency energy, pressureand gap control to effectively seal or fuse tissue between two opposingjaw members or sealing plates. Vessel or tissue sealing is more than“cauterization” which is defined as the use of heat to destroy tissue(also called “diathermy” or “electrodiathermy”) and vessel sealing ismore than “coagulation” which is defined as a process of desiccatingtissue wherein the tissue cells are ruptured and dried. “Vessel sealing”is defined as the process of liquefying the collagen, elastin and groundsubstances in the tissue so that it reforms into a fused mass withsignificantly-reduced demarcation between the opposing tissuestructures.

In order to effectively “seal” tissue or vessels, two predominantmechanical parameters must be accurately controlled: 1) the pressureapplied to the vessel or tissue; and 2) the gap distance between theconductive tissue contacting surfaces (electrodes). As can beappreciated, both of these parameters are affected by the thickness ofthe tissue being sealed. Accurate application of pressure is importantfor several reasons: to reduce the tissue impedance to a low enoughvalue that allows enough electrosurgical energy through the tissue; toovercome the forces of expansion during tissue heating; and tocontribute to the end tissue thickness which is an indication of a goodseal. It has been determined that a good seal for certain tissues isoptimum between 0.001 inches and 0.006 inches.

With respect to smaller vessels or tissue, the pressure applied becomesless relevant and the gap distance between the electrically conductivesurfaces becomes more significant for effective sealing. In other words,the chances of the two electrically conductive surfaces touching duringactivation increases as the tissue thickness and the vessels becomesmaller.

Commonly owned, U.S. Pat. No. 6,511,480, PCT Patent Application Nos.PCT/US01/11420 and PCT/US01/11218, U.S. patent application Ser. Nos.10/116,824, 10/284,562 and 10/299,650 all describe various open surgicalforceps which seal tissue and vessels. All of these references arehereby incorporated by reference herein. In addition, several journalarticles have disclosed methods for sealing small blood vessels usingelectrosurgery. An article entitled Studies on Coagulation and theDevelopment of an Automatic Computerized Bipolar Coagulator, J.Neurosurg., Volume 75, July 1991, describes a bipolar coagulator whichis used to seal small blood vessels. The article states that it is notpossible to safely coagulate arteries with a diameter larger than 2 to2.5 mm. A second article is entitled Automatically Controlled BipolarElectrocoagulation—“COA-COMP”, Neurosurg. Rev. (1984), pp. 187-190,describes a method for terminating electrosurgical power to the vesselso that charring of the vessel walls can be avoided.

Typically and particularly with respect to open electrosurgicalprocedures, once a vessel is sealed, the surgeon has to remove thesealing instrument from the operative site, substitute a new instrumentand accurately sever the vessel along the newly formed tissue seal. Ascan be appreciated, this additional step may be both time consuming(particularly when sealing a significant number of vessels) and maycontribute to imprecise separation of the tissue along the sealing linedue to the misalignment or misplacement of the severing instrument alongthe center of the tissue sealing line.

Many endoscopic vessel sealing instruments have been designed whichincorporate a knife or blade member which effectively severs the tissueafter forming a tissue seal. For example, commonly-owned U.S.application Ser. Nos. 10/116,944; 10/179,863; and 10/460,926 alldescribe endoscopic instruments which effectively seals and cuts tissuealong the tissue seal. Other instruments include blade members orshearing members which simply cut tissue in a mechanical and/orelectromechanical manner and are relatively ineffective for vesselsealing purposes.

There exists a need to develop an open electrosurgical forceps which issimple, reliable and inexpensive to manufacture and which effectivelyseals tissue and vessels and which allows a surgeon to utilize the sameinstrument to effectively sever the tissue along the newly formed tissueseal.

SUMMARY

Forceps for use in open surgical procedures are provided. According toone aspect of the present disclosure, an open electrosurgical forcepsfor sealing tissue is provided. The forceps includes first and secondshaft portions pivotably associated with one another. Each shaft portionhas a jaw member disposed at a distal end thereof. The jaw members aremovable from a first position in spaced relation relative to one anotherto at least one subsequent position wherein the jaw members cooperate tograsp tissue therebetween. Each of the jaw members includes anelectrically conductive sealing surface for communicatingelectrosurgical energy through tissue held therebetween. At least one ofthe jaw members includes a slot formed through the sealing surfacethereof.

The forceps further includes a cutting mechanism operatively associatedwith the first and second jaw members. The cutting mechanism includes acutting element disposed within the slot of the at least one jaw member.The cutting element is movable from a first position wherein the cuttingelement is retracted within the slot of the at least one jaw member anda second position in which the cutting element at least partiallyprojects from the sealing surface of the at least one jaw member. Thecutting mechanism further includes an actuator operatively associatedwith the cutting element which upon movement thereof selectivelyadvances the cutting element from the first position to the secondpositions.

In one embodiment, the actuator is integrally associated with thecutting element. The cutting mechanism is pivotable about a pivot whichconnects the first and second jaw members. The actuator is spaced adistance from the first shaft portion. The actuator selectivelyactivates the cutting element when moved relative to the first shaftportion.

In another embodiment, the cutting mechanism may include a drive rodextending through a channel formed in at least one of the first andsecond shaft portions. The drive rod includes a distal end operativelyconnected to the cutting element. The cutting mechanism may furtherinclude a tab operatively connected to the drive rod for manipulatingthe drive rod to urge the cutting element between the first and secondpositions.

The cutting element is supported in the slot of the jaw member such thatproximal displacement of the drive rod urges the cutting element fromwithin the slot of the jaw member to cut tissue. Desirably, the cuttingelement includes at least one angled slot defined therethrough whichreceives a pivot pin fixed to one of the jaw members.

In one embodiment, each angled slot formed in the cutting elementincludes a first portion in close proximity to the sealing surface and asecond portion extending distally and away from the sealing surface.Proximal movement of the drive rod urges the cutting element from thefirst position to the second position by a camming action between thepin and the slot formed in the cutting element.

The open electrosurgical forceps may further include a biasing elementfor urging the drive rod to a distal-most position. The cutting elementis pivotably disposed within the slot of the jaw member. The cuttingelement projects out through the jaw member and defines a cammingsurface.

In one embodiment, the second shaft portion reciprocably supports theactuator. The actuator is movable from a first position spaced from thecutting element to a second position in contact with the cuttingelement. In use, displacement of the actuator from the first position tothe second position, the actuator engages the camming surface of thecutting element and urges the cutting element from the first position tothe second position.

The open electrosurgical forceps may further include a biasing elementfor urging the cutting element to the first position. It is envisionedthat movement of the actuator pivots the cutting element between thefirst and second positions.

According to another aspect of the present disclosure, the openelectrosurgical forceps may include a pair of shaft portions pivotablycoupled to one another at a pivot point. Each shaft portion includes ajaw member at a distal end thereof for grasping tissue therebetween.Each jaw member includes a sealing surface for conductingelectrosurgical energy through tissue grasped therebetween and one ofthe sealing surfaces has a slot formed therein. The forceps furtherincludes a cutting mechanism operatively coupled to the shaft portionsand has a cutting element operatively secured proximate the distal endof the forceps. The cutting mechanism is selectively movable from afirst position in which the cutting element is retracted within the slotand a second position in which the cutting element at least partiallyprojects from the slot to cut tissue disposed between the jaw members.

In one embodiment, the cutting mechanism includes a drive rod extendingthrough a channel formed in at least one of the first and second shaftportions. The drive rod includes a distal end operatively connected tothe cutting element. The cutting mechanism further includes a taboperatively connected to the drive rod for manipulating the drive rod tourge the cutting element between the first and second positions.

The cutting element is operatively engaged in the slot of the one jawmember such that axial displacement of the drive rod results intransverse displacement of the cutting element from the slot to cuttissue disposed between jaw members.

DESCRIPTION OF THE DRAWINGS

Various embodiments of the present disclosure are described withreference to the following drawing figures. It should be understood,however, that the drawings are designed for the purpose of illustrationonly and not as a definition of the limits of the invention.

FIG. 1A is a perspective view of a forceps according to one embodimentof the present disclosure;

FIG. 1B is a side, elevational view of the forceps of FIG. 1A shown inan open position;

FIG. 1C is a side, elevational view of the forceps of FIGS. 1A and 1Bshown in a closed position and the cutting assembly shown in anunactuated position;

FIG. 1D is a side, elevational view of the forceps of FIGS. 1A-1C shownin a closed position and the cutting assembly shown in an actuatedposition;

FIG. 2A is a cross-sectional, side elevational view of an alternateembodiment of a forceps according to the present disclosure;

FIG. 2B is an enlarged view of the indicated area of detail of FIG. 2A,illustrating a cutting element of the forceps in a first position;

FIG. 2C is an enlarged view of the indicated area of detail of FIG. 2A,illustrating the cutting element of the forceps in a second position;

FIG. 2D is an enlarged view of the indicated area of detail of FIG. 2A,illustrating a cutting element of the forceps according to an alternateembodiment of the disclosure;

FIG. 3A is an enlarged, schematic side elevational view of a distal endof a forceps constructed according to another embodiment of the presentdisclosure, illustrating a cutting assembly in a first position;

FIG. 3B is an enlarged, schematic side elevational view of the distalend of the forceps of FIG. 3A, illustrating the cutting assembly in asecond position;

FIG. 3C is an enlarged, schematic view of an alternate biasingarrangement for the cutting assembly shown in a first position;

FIG. 3D is an enlarged, schematic view of an alternate biasingarrangement of FIG. 3C in a second position;

FIG. 4A is an enlarged schematic side elevational view of a distal endof a forceps constructed according to yet another embodiment of thepresent disclosure, illustrating a cutting assembly in a first position;and

FIG. 4B is an enlarged schematic side elevational view of the distal endof the forceps of FIG. 4A, illustrating the cutting assembly in a secondposition.

DETAILED DESCRIPTION

Referring now to FIGS. 1A-1D, a forceps or hemostat for use in opensurgical procedures is generally designated as 100. Forceps 100 includesa first elongated shaft portion 110 and a second elongated shaft portion120 each having a proximal end 112 and 122, respectively. In thedrawings and in the descriptions which follow, the term “proximal”, asis traditional, will refer to the end of forceps 100 which is closer tothe user, while the term “distal” will refer to the end which is furtherfrom the user.

Forceps 100 includes an end effector assembly 130 which attaches todistal ends 114, 124 of shaft portions 110, 120, respectively. Asexplained in more detail below, end effector assembly 130 includes apair of opposing jaw members 132, 134 which are pivotably connectedabout a pivot pin 135 and which are movable relative to one another tograsp tissue therebetween.

Each shaft portion 110 and 120 includes a handle 116, 126, respectively,disposed at proximal ends 112, 122, thereof. Each handle 116, 126defines a finger hole 116 a, 126 a, respectively, therethrough forreceiving a finger of the user. As can be appreciated, finger holes 116a, 126 a, facilitate movement of shaft portions 110 and 120 relative toone another which, in turn, pivot the jaw members 132 and 134, aboutpivot pin 135, from an open position wherein the jaw members 132 and 134are disposed in spaced relation relative to one another to a clamping orclosed position wherein jaw members 132 and 134 cooperate to grasptissue therebetween.

Shaft portions 110, 120 are designed to transmit a particular desiredforce to the opposing sealing surfaces 132 a, 134 a of jaw members 132,134, respectively, when clamped. In particular, since shaft portions110, 120 effectively act together in a spring-like manner (i.e., bendingthat behaves like a spring), the length, width, height and deflection ofshaft portions 110, 120 will directly effect the overall transmittedforce imposed on opposing jaw members 132, 134. Jaw members 132, 134 aremore rigid than shaft portions 110, 120 and the strain energy stored inthe shaft portions 110, 120 provides a constant closure force betweenjaw members 132, 134.

Each shaft portion 110, 120 also includes a ratchet portion 118, 128.Each ratchet, e.g., 118, extends from a proximal end of its respectiveshaft portion 110 towards the other ratchet 128 in a generallyvertically aligned manner. The inner facing surfaces of each ratchet118, 128 includes a plurality of flanges 118 a, 128 a, respectively,which project from the inner facing surface of each ratchet 118, 128such that the ratchets 118, 128 can interlock in at least one position.In the embodiment shown in FIG. 1A, ratchets 118, 128 interlock atseveral different positions. Each ratchet position holds a specific,i.e., constant, strain energy in shaft portions 110, 120 which, in turn,transmits a specific force to jaw members 132, 134.

One of the shaft portions, e.g., shaft portion 120, includes a proximalshaft connector 150 which is designed to connect forceps 100 to a sourceof electrosurgical energy, e.g., an electrosurgical generator (notshown). Connector 150 electromechanically engages a conducting cable 152such that the user may selectively apply electrosurgical energy asneeded.

As briefly discussed above, jaw members 132, 134 are selectively movableabout pivot pin 135 from the open position to the closed position forgrasping tissue therebetween. Jaw members 132 and 134 are generallysymmetrical and include similar component features which cooperate topermit facile rotation about pivot pin 135 to effect the grasping andsealing of tissue. As a result and unless otherwise noted, jaw member132 and the operative features associated therewith are initiallydescribed herein in detail and the similar component features withrespect to jaw member 134 will be briefly summarized thereafter.Moreover, many of the features of jaw members 132 and 134 are describedin detail in commonly-owned U.S. patent application Ser. Nos.10/284,562, 10/116,824, 09/425,696, 09/178,027 and PCT Application Ser.No. PCT/US01/11420 the contents of which are all hereby incorporated byreference in their entirety herein.

Jaw member 132 includes an electrically conductive sealing surface 132 awhich conducts electrosurgical energy of a first potential to the tissueupon activation of forceps 100. Exemplary embodiments of conductivesealing surface 132 a are discussed in commonly-owned, co-pending PCTApplication Serial No. PCT/US01/11412 and commonly owned, co-pending PCTApplication Serial No. PCT/US01/11411, the contents of both of theseapplications being incorporated by reference herein in their entirety.

Similar to jaw member 132, jaw member 134 includes an electricallyconductive sealing surface 134 a for conducting electrosurgical energyof a second potential to the tissue upon activation of forceps 100.

It is envisioned that one of the jaw members, e.g., 132, includes atleast one stop member (not shown) disposed on the inner facing surfaceof the electrically conductive sealing surface 132 a (and/or 134 a).Alternatively or in addition, the stop member(s) may be positionedadjacent to the electrically conductive sealing surfaces 132 a, 134 a orproximate the pivot pin 135. The stop member(s) is/are designed todefine a gap between opposing jaw members 132 and 134 during sealing.The separation distance during sealing or the gap distance is within therange of about 0.001 inches (˜0.03 millimeters) to about 0.006 inches(˜0.016 millimeters).

A detailed discussion of these and other envisioned stop members as wellas various manufacturing and assembling processes for attaching,disposing, depositing and/or affixing the stop members to theelectrically conductive sealing surfaces 132 a, 134 a are described incommonly-assigned, co-pending PCT Application Serial No. PCT/US01/11222and U.S. application Ser. No. 10/471,818 which are both herebyincorporated by reference in their entirety herein.

As mentioned above, two mechanical factors play an important role indetermining the resulting thickness of the sealed tissue andeffectiveness of the seal, i.e., the pressure applied between opposingjaw members 132 and 134 and the size of the gap between opposing jawmembers 132 and 134 (or opposing sealing surface 132 a and 134 a duringactivation). It is known that the thickness of the resulting tissue sealcannot be adequately controlled by force alone. In other words, too muchforce and jaw members 132 and 134 may touch and possibly short resultingin little energy traveling through the tissue thus resulting in aninadequate seal. Too little force and the seal would be too thick.Applying the correct force is also important for other reasons: tooppose the walls of the vessel; to reduce the tissue impedance to a lowenough value that allows enough current through the tissue; and toovercome the forces of expansion during tissue heating in addition tocontributing towards creating the required end tissue thickness which isan indication of a good seal.

Sealing surfaces 132 a and 134 a are relatively flat to avoid currentconcentrations at sharp edges and to avoid arcing between high points.In addition, and due to the reaction force of the tissue when engaged,jaw members 132 and 134 are manufactured to resist bending, i.e.,tapered along their length to provide a constant pressure for a constanttissue thickness at parallel and the thicker proximal portion of jawmembers 132 and 134 will resist bending due to the reaction force of thetissue.

As best shown in FIGS. 1A-1D, forceps 100 further includes a cuttingmechanism 140 operatively associated therewith. Cutting mechanism 140includes an arm portion 142 pivotably connected to one of the first andsecond shaft portions 110, 120, a cutting element 144 (e.g., blade,knife, scalpel, etc.) disposed at a distal end 146 a thereof, and afinger gripping element 148 disposed at a proximal end 146 b thereof.

Cutting mechanism 140 is pivotably coupled to shaft portion 110 aboutpivot pin 135. Cutting mechanism 140 is pivotably coupled to shaftportion 110 in such a manner that cutting element 144 is biased (via aspring or the like) in a retracted position within a slot 134 b definedin sealing surface 134 a of jaw member 134. Cutting mechanism 140 isselectively movable about pivot pin 135 to deploy cutting element 144from within slot 134 b to cut tissue. Cutting element 144 may also bemovably retractable depending upon a particular purpose.

In particular, cutting mechanism 140 is pivotable from a first positionin which cutting element 144 is retained at least substantially withinslot 134 b of jaw member 134 to a second position in which cuttingelement 144 is deployed from jaw member 134. When cutting element 144 isdisposed in jaw member 134, arm portion 142 of cutting assembly 142 isspaced a distance from shaft portion 110.

With reference to FIGS. 1B-1D, a method of using forceps 100 will now bedescribed in detail. As seen in FIG. 1B, with shaft portions 110, 120 inthe open position, such that jaw members 132, 134 are spaced from oneanother, and with cutting assembly 140 in the first position (i.e.,within slot 134 b), jaw members 132, 134 are maneuvered around thetarget tissue “T”. As seen in FIG. 1C, following manipulation andpositioning of jaw members 132, 134 about target tissue “T”, forceps 100is moved from the open position to the closed position. In particular,proximal ends 112, 122 of shaft portions 110 and 120 are moved towardone another, in the direction of arrows “A”, to thereby proximate jawmembers 132, 134 toward one another.

In so doing, target tissue “T” is clamped or grasped between jaw members132, 134. Desirably, the user then activates a hand switch or a footswitch (not shown) to provide electrosurgical energy to each jaw member132, 134 to communicate energy through target tissue “T” heldtherebetween to effect a tissue seal. Once target tissue “T” is sealed,as seen in FIG. 1D, cutting mechanism 140 is actuated, e.g., arm portion142 is moved toward shaft portion 110 in the direction of arrow “B”, tosever target tissue “T” along the tissue seal. In particular, uponmovement of arm portion 142 cutting element 144 pivots about pivot pin135 and deploys from jaw member 134 toward jaw member 132 to therebyslice, cut and/or otherwise divide target tissue “T” along thepreviously formed tissue seal.

Turing now to FIGS. 2A-2C, a forceps in accordance with anotherembodiment of the present disclosure is shown generally as 200. Forceps200 is similar to forceps 100 and will only be described in detail tothe extent necessary to identify differences in construction andoperation.

Forceps 200 includes a cutting mechanism 240 operatively associatedtherewith. Cutting mechanism 240 includes a drive rod 242 for advancingcutting mechanism 240 through shaft portion 210, which will be explainedin greater detail below. Drive rod 242 includes a distal end 242 aconfigured to mechanically support a cutting element 244. Cuttingelement 244 is disposed in slot 234 b formed in seal surface 234 a ofjaw member 234 (see FIG. 2B). Cutting mechanism 240 further includes afinger tab 246 operatively associated with drive rod 242 such thatmovement of finger tab 246 moves drive rod 242 in the correspondingdirection.

Shaft portion 210 includes at least one guide channel 222 formed thereinfor controlling and/or guiding drive rod 242 through movementtherethrough. Drive rod 242 is made from a flexible wire or plasticsheath which does not buckle upon movement thereof.

A spring 248 may be employed within guide channel 222 to bias cuttingmechanism 240 back to the unactuated position upon proximal movement oftab 246 such that upon release of finger tab 246, the force of spring248 automatically returns cutting mechanism 240 to its distal-mostposition within guide channel 222 which, in turn, retracts cuttingelement 244 within slot 234. While a spring 248 is shown for maintainingcutting mechanism 240 in a distal-most position, it is envisioned andwithin the scope of the present disclosure that a spring, e.g., a coilspring, (not shown) can be operatively associated therewith formaintaining cutting mechanism 240 in a proximal-most position andwherein finger tab 246 is positioned so as to drive cutting mechanism240 in a distal direction.

As best seen in FIGS. 2B and 2C, cutting element 244 is provided with atleast one elongated slot, preferably a pair of elongated slots 244 a,244 b, formed therein. Slots 244 a, 244 b are oriented at an angle withrespect to the longitudinal axis of forceps 200. The portion of slots244 a, 244 b which is closest to seal surface 234 a of jaw member 234 islocated proximal of the portion of slots 244 a, 244 b which is furthestfrom seal surface 234 a of jaw member 234.

A pin 250 is provided within each slot 244 a, 244 b. Each pin 250 isfixedly positioned relative to jaw member 234. When cutting element 244is in a distal-most position, pins 250 are located in the portion ofslots 244 a, 244 b closest to seal surface 234 a.

As seen in FIGS. 2B and 2C, in operation and following application ofelectrosurgical energy to jaw members 232, 234, to thereby seal thetarget tissue held therebetween, the user activates finger tab 246 tothereby urge drive rod 242 in a proximal direction, as indicated byarrow “A”. In so doing, cutting element 244 is urged in an angulardirection relative to the longitudinal axis, as indicated by arrows “B”.In particular, cutting element 244 is drawn both proximally and towardjaw member 232 (i.e., deployed from slot 234 b formed in sealing surface234 a of jaw member 234, to thereby slice the target tissue which isclamped between jaw members 232, 234. In other words, cutting element244 is drawn in direction “B” by the camming action created betweenslots 244 a, 244 b and pins 250. While cam slots 244 a, 244 b may bediagonal, as seen in FIG. 2D, cutting element 244 may be provided withcam slots 244 a′ and 244 b′ having a diagonal portion and alongitudinally extending portion integrally connected to the diagonalportion to thereby by create a slicing or cutting motion for cuttingelement 244.

Following the cutting of the target tissue, finger tab 246 may bereleased to thereby allow the force of spring 248 to automaticallyreturn cutting mechanism 240 to its distal-most position within guidechannel 222 for subsequent sealing and cutting, which, as mentionedabove, retract cutting element 244 to within slot 234 b.

Turing now to FIGS. 3A-3D, a forceps 300, having a distal end inaccordance with another embodiment of the present disclosure, is shown.Forceps 300 is similar to forceps 100 and 200 and will only be describedin detail to the extent necessary to identify differences inconstruction and operation.

Forceps 300 includes a cutting mechanism 340 operatively associatedtherewith. Cutting mechanism 340 includes a cutting element 344 disposedin slot 334 b formed in sealing surface 334 a of jaw member 334. Cuttingelement 344 includes a camming surface 346 at a rear portion thereof,i.e., which extends outwardly from a side opposite sealing surface 334 aof jaw member 334.

Cutting element 344 is pivotably supported in slot 334 b by a pivot pin350. A biasing member 348, e.g., a torsion spring or the like, may beemployed within jaw member 334 to bias cutting element 344 in aretracted, i.e., undeployed, condition. Upon at least partial deploymentof cutting element 344, biasing member 348 is biased such that uponrelease of cutting element 344, the force of the biasing member 348automatically returns cutting element 344 into jaw member 334. Cuttingmechanism 340 further includes an advancing sheath 342 operativelyassociated with forceps 300 for deploying cutting element 344. Any typeof known actuation may be employed to advance sheath 342.

As seen in FIGS. 3A and 3B, following application of electrosurgicalenergy to jaw members 132, 134 to seal tissue held therebetween, theuser advances sheath 342 a distal direction, as indicated by arrow “A”,to engage camming surface 346 of cutting element 344 and urge cuttingelement 344 out of slot 334 b in the direction of arrow “B” to severtissue. Following the cutting of the tissue, sheath 342 is withdrawn ina proximal direction until camming surface 346 of cutting element 344 isdisengaged. The force of biasing member 348 automatically returnscutting mechanism 340 into slot 334 b of jaw member 334.

Turning now to FIGS. 3C and 3D, a detailed discussion of biasing member348 is provided. As seen in FIG. 3C, cutting element 344 includes a rearflange or arm 360 which defines a notch 362 formed between a proximalend of cutting element 344 and arm 360. Notch 362 is located proximal ofpin 350. Notch 362 extends through cutting edge 347 of cutting element344. Cutting element 344 is fabricated from spring type steel or anyother material exhibiting resilient characteristics.

In operation, as seen in FIGS. 3C and 3D, as cutting element 344 isurged out of slot 334 b of jaw member 334, in the direction of arrow “B”(FIG. 3B), notch 362 closes against the bias created by arm 360.Following the cutting of the target tissue, sheath 342 is withdrawn in aproximal direction until camming surface 346 of cutting element 344 isdisengaged. The biasing force created by arm 360 automatically returnscutting mechanism 340 into slot 334 b of jaw member 334.

Turning now to FIGS. 4A and 4B an alternative embodiment includes acutting element 444 is pivotably connected to a drive rod 452 by a pin454. In this manner, as drive rod 452 is driven in a distal direction,as indicated by arrow “A”, cutting element 444 is pivoted about pin 450and urged out of slot 334 b of jaw member 334. Following the cuttingstep, drive rod 452 is withdrawn in a proximal direction to urge cuttingelement 444 back into jaw member 334.

It is envisioned and within the scope of the present disclosure that abiasing member, e.g., a spring, (not shown) may be provided forreturning cutting element 444 into jaw member 334 following deploymentby drive rod 452.

It is further envisioned and within the scope of the present disclosureto provide a cutting element 444 configured such that cutting element444 is pivotable about pivot pin 435.

It is envisioned that any of the cutting elements disclosed herein maybe fabricated from plastic and/or metal (e.g., stainless steel,titanium, etc.). Desirably, the cutting elements are fabricated fromnon-conductive materials to thereby reduce the potential for straycurrents and/or shorting.

From the foregoing and with reference to the various figure drawings,those skilled in the art will appreciate that certain modifications canalso be made to the present disclosure without departing from the scopeof the same. For example, none of the aforedescribed forceps requirethat the tissue be necessarily cut after sealing or that the tissue besealed prior to cutting. As can be appreciated, this gives the useradditional flexibility when using the instrument.

For example, it is also contemplated that forceps 100, 200 and/or 300(and/or the electrosurgical generator used in connection therewith) mayinclude a sensor or feedback mechanism (not shown) which automaticallyselects the appropriate amount of electrosurgical energy to effectivelyseal the particularly-sized tissue grasped between the jaw members. Thesensor or feedback mechanism may also measure the impedance across thetissue during sealing and provide an indicator (visual and/or audible)that an effective seal has been created between jaw members 132 and 134.Commonly-owned U.S. patent application Ser. No. 10/073,761, filed onFeb. 11, 2002, entitled “Vessel Sealing System”; U.S. patent applicationSer. No. 10/626,390, filed on Jul. 24, 2003, entitled “Vessel SealingSystem”; U.S. patent application Ser. No. 10/427,832, filed on May 1,2003, entitled “Method and System for Controlling Output of RF MedicalGenerator”; U.S. patent application Ser. No. 10/761,524, filed on Jan.21, 2004, entitled “Vessel Sealing System”; U.S. Provisional ApplicationNo. 60/539,804, filed on Jan. 27, 2004, entitled “Method of TissueFusion of Soft Tissue by Controlling ES Output Along Optimal ImpedanceCurve”; U.S. Provisional Application No. 60/466,954; filed on May 1,2003, entitled “Method and System for Programming and Controlling anElectrosurgical Generator System”; and U.S. Pat. No. 6,398,779, discloseseveral different types of sensory feedback mechanisms and algorithmswhich may be utilized for this purpose. The contents of theseapplications are hereby incorporated by reference herein.

Experimental results suggest that the magnitude of pressure exerted onthe tissue by the sealing surfaces of jaw members 132 and 134 areimportant in assuring a proper surgical outcome. Tissue pressures withina working range of about 3 kg/cm² to about 16 kg/cm² and, desirably,within a working range of 7 kg/cm² to 13 kg/cm² have been shown to beeffective for sealing arteries and vascular bundles. Tissue pressureswithin the range of about 4 kg/cm² to about 6.5 kg/cm² have proven to beparticularly effective in sealing arteries and particular tissuebundles.

While several embodiments of the disclosure have been shown in thedrawings, it is not intended that the disclosure be limited thereto, asit is intended that the disclosure be as broad in scope as the art willallow and that the specification be read likewise. Therefore, the abovedescription should not be construed as limiting, but merely asexemplifications of preferred embodiments. Those skilled in the art willenvision other modifications within the scope and spirit of the claimsappended hereto.

1. An open electrosurgical forceps for sealing tissue, comprising: firstand second shaft portions pivotably associated with one another, eachshaft portion having a jaw member disposed at a distal end thereof, thejaw members being movable from a first position in spaced relationrelative to one another to at least one subsequent position wherein thejaw members cooperate to grasp tissue therebetween, each of the jawmembers including an electrically conductive sealing surface beingconfigured to communicate electrosurgical energy through tissue heldtherebetween, at least one of the jaw members including a slot formedthrough the sealing surface thereof; a cutting mechanism operativelyassociated with the first and second jaw members, the cutting mechanismincluding: a cutting element disposed within the slot of the at leastone jaw member, the cutting element being movable about a pivot from afirst position wherein the cutting element is retracted within the atleast one jaw member and a second position in which a cutting edge ofthe cutting element at least partially projects from a sealing surfaceof the at least one jaw member, the cutting element including a biasingmember at a proximal end thereof, the biasing member operably disposedwithin the jaw member and configured for biasing the cutting elementtoward the first position and pivoting the cutting element, the biasingmember including a notched portion configured to facilitate pivoting thecutting element between the first and second positions, the notchedportion disposed proximal relative to the pivot and extending to thecutting edge of the cutting element; and an actuator operativelyassociated with the cutting element which upon movement thereofselectively advances the cutting element from the first position to thesecond position.
 2. The open electrosurgical forceps according to claim1, wherein the cutting element is pivotably disposed within the slot ofthe jaw member.
 3. The open electrosurgical forceps according to claim1, wherein the cutting element extends out through the jaw member anddefines a camming surface.
 4. The open electrosurgical forceps accordingto claim 3, wherein the second shaft portion reciprocably supports theactuator, the actuator being movable from a first position spaced fromthe cutting element to a second position in contact with the cuttingelement.
 5. The open electrosurgical forceps according to claim 4,wherein upon displacement of the actuator from the first position to thesecond position, the actuator engages the camming surface of the cuttingelement and urges the cutting element from the first position to thesecond position.
 6. The open electrosurgical forceps according to claim1, wherein the biasing member located at the proximal end of the cuttingelement is a torsion spring.
 7. The open electrosurgical forcepsaccording to claim 4, wherein movement of the actuator pivots thecutting element between the first and second positions.
 8. An openelectrosurgical forceps for sealing tissue, comprising: a pair of shaftportions pivotably coupled to one another at a first pivot, each shaftportion including a jaw member at a distal end thereof for graspingtissue therebetween, each jaw member including a sealing surface adaptedto conduct electrosurgical energy through tissue grasped therebetweenand one of the sealing surfaces includes a slot defined therein; acutting mechanism operatively coupled to at least one of the pair ofshaft portions, the cutting mechanism comprising: a cutting elementpivotably coupled to at least one of the jaw members and configured topivot within the slot, the cutting mechanism being selectively moveableabout a second pivot from a first position in which the cutting elementis retracted within the slot and a second position in which a cuttingedge of the cutting element at least partially projects from the slot tocut tissue disposed between the jaw members; a biasing member operablydisposed on the cutting element and within the jaw member, the biasingmember configured for biasing the cutting element toward the firstposition and pivoting the cutting element about the second pivot, thebiasing member including a notched portion configured to facilitatepivoting the cutting element between the first and second positionsabout the second pivot, the notched portion disposed proximal relativeto the second pivot and extending to the cutting edge of the cuttingelement; and an actuator operatively associated with the cutting elementthat, upon movement thereof, selectively pivots the cutting element fromthe first position to the second position, wherein the cutting elementpivots with respect to the actuator.
 9. The open electrosurgical forcepsaccording to claim 8, wherein the actuator is integrally associated withthe cutting element.
 10. The open electrosurgical forceps according toclaim 8, wherein the actuator is pivotably coupled to the cuttingelement.
 11. The open electrosurgical forceps according to claim 8,wherein the actuator is spaced a distance from a first shaft portion.12. The open electrosurgical forceps according to claim 8, wherein theactuator selectively activates the cutting element when moved relativeto a first shaft portion.
 13. The open electrosurgical forceps accordingto claim 8, wherein the actuator is a drive rod.